Search results for "ROUGHNESS"

2017

Dielectric loaded surface plasmon waveguides (DLSPPWs) comprised of polymer ridges deposited on top of CMOS compatible metal thin films are investigated at telecom wavelengths. We perform a direct comparison of the properties of copper (Cu), aluminum (Al), titanium nitride (TiN) and gold (Au) based waveguides by implementing the same plasmonic waveguiding configuration for each metal. The DLSPPWs are characterized by leakage radiation microscopy and a fiber-to-fiber configuration mimicking the cut-back method. We introduce the ohmic loss rate (OLR) to analyze quantitatively the properties of the CMOS metal based DLSPPWs relative to the corresponding Au based waveguides. We show that the Cu,…

Effect of surface treatments with acid solutions on the surface roughness of an Yttrium-Tetragonal Zirconia Polycrystal.

2017

Background The purpose of this in vitro study was to evaluate the effect of conventional surface treatment with acid solutions on the surface roughness of a zirconia-based ceramic. Material and methods Specimens of yttrium-tetragonal zirconia polycrystal (Y-TZP) -based ceramic were fabricated (5.0 x 5.0 x 2.0 mm, n=40). The specimens were submitted to the tested surface treatment method and divided into 4 groups (n=10): no treatment-control (GI), airborne 110 µm aluminum oxide particle abrasion for 1 minute-conventional method (GII); etching with 48% hydrofluoric acid for 2 minutes (GIII), and nitric acid/hydrofluoric acid etching for 2 minutes (GIV). The surface roughness (Ra) test was per…

Formation of surface roughness on nanocrystalline aluminum samples under straining by molecular dynamics studies

2006

International audience; The surface roughening of nanocrystalline aluminum samples was investigated by molecular dynamics simulations. Attention was focused on the fact that roughness increases with the grain size and the strain. The elastic-plastic transition was found at around 3.5% strain and a reverse Hall-Petch effect was observed under straining conditions. Then, different strain distributions in grains and grain boundaries at the samples surface was highlighted, yielding to the formation of local roughness. Finally, a linear relationship between the magnitude of roughness and the out-of-plane strain component was found.

Surface Periodic Domain Engineering in Congruent Lithium Tantalate Crystals

2006

First experiments with the novel electric field Surface Periodic Poling technique have been carried out on Lithium Tantalate. Optimal poling parameters gave 50:50 mark-to-space ratio in the micron scale with good uniformity and high repeatability.

Pore shape affects the determination of the pore size of ordered mesoporous silicas by mercury intrusion.

2008

MCM-41 and SBA-15 micelle-templated silicas are ideal reference materials to study the effect of surface roughness on pore size measurement by mercury intrusion, as the inner surface of the mesoporous channels is much rougher in the case of SBA-15 than MCM-41. In the case of MCM-41, the pressure of mercury intrusion is related to the pore size by the classical Washburn−Laplace law, while in the case of SBA-15, the pressure of intrusion is much higher than expected and classical models underevaluate the size of the channels. Defects on the pore surface of SBA-15 affect the mercury intrusion in a similar way as the deviation from cylindrical geometry does for the pores of spongelike silica gl…

Nanoporous kaolin

2017

Cellulose nano- and microfibrils (CNF/CMF) grades vary significantly based on the raw materials and process treatments used. In this study four different CNF/CMF grades were combined with kaolin clay pigment particles to form nanoporous composites. The attained composite properties like porosity, surface smoothness, mechanical properties and density properties depended strongly on the raw materials used. In general, higher kaolin content (~80 wt%) led to controllable shrinkage during drying, which resulted in improved dimensional stability of composites, compared to a lower kaolin content (~50 wt%). On the other hand, the use of a plasticizer and a high amount of CNF/CMF was essential to pr…

Influence of titanium-substrate roughness on Ca–P–O thin films grown by atomic layer deposition

2013

Abstract Amorphous Ca–P–O films were deposited on titanium substrates using atomic layer deposition, while maintaining a uniform Ca/P pulsing ratio of 6/1 with varying number of atomic layer deposition cycles starting from 10 up to 208. Prior to film deposition the titanium substrates were mechanically abraded using SiC abrasive paper of 600, 1200, 2000 grit size and polished with 3 μm diamond paste to obtain surface roughness R rms values of 0.31 μm, 0.26 μm, 0.16 μm, and 0.10 μm, respectively. The composition and film thickness of as-deposited amorphous films were studied using Time-Of-Flight Elastic Recoil Detection Analysis. The results showed that uniform films could be deposited on ro…

Nucleation and growth of ZnO on PMMA by low-temperature atomic layer deposition

2015

ZnO films were grown by atomic layer deposition at 35 °C on poly(methyl methacrylate) substrates using diethylzinc and water precursors. The film growth, morphology, and crystallinity were studied using Rutherford backscattering spectrometry, time-of-flight elastic recoil detection analysis, atomic force microscopy, scanning electron microscopy, and x-ray diffraction. The uniform film growth was reached after several hundreds of deposition cycles, preceded by the precursor penetration into the porous bulk and island-type growth. After the full surface coverage, the ZnO films were stoichiometric, and consisted of large grains (diameter 30 nm) with a film surface roughness up to 6 nm (RMS). T…

Minimizing coherent thermal conductance by controlling the periodicity of two-dimensional phononic crystals

2019

Periodic hole array phononic crystals (PnC) can strongly modify the phonon dispersion relations, and have been shown to influence thermal conductance coherently, especially at low temperatures where scattering is suppressed. One very important parameter influencing this effect is the period of the structure. Here, we measured the sub-Kelvin thermal conductance of nanofabricated PnCs with identical hole filling factors, but three different periodicities, 4, 8, and 16 $\mu$m, using superconducting tunnel junction thermometry. We found that all the measured samples can suppress thermal conductance by an order of magnitude, and have a lower thermal conductance than the previously measured small…

Sensitivity analysis on the relationship between vegetation growth and multi-polarized radar data

2009

Spatially distributed soil moisture is required for watershed applications such as drought and flood prediction, crop irrigation scheduling, etc. In particular, an accurate assessment of the spatial and temporal variation of soil moisture is necessary to improve the predictive capability of runoff models, and for improving and validating hydrological processes forecasting. In recent years, several models have been developed in order to retrieve soil moisture using RADAR data. However, these models need precise prior knowledge about surface roughness. Within this framework, the present research aims to investigate the capabilities of multi polarimetric RADAR images to overcome the use of in …